![\""\u00a9\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/4\/2021\/11\/potw2140a-1cd8631.jpg?quality=90&resize=620%2C412"\" "\\"\"\u00a9\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Captured by the Hubble Space Telescope, these two galaxies are caught in a dangerous dance that will culminate \u2013 at some point in the very, very distant future \u2013 in their merging.<\/p>\n
They are likely to have been dancing for the last billion years, and it could be another billion before they become one.<\/p>\n
\u201cThese are two galaxies having a bad day,\u201d says Prof Chris Lintott<\/a>, astronomer at the University of Oxford and presenter for BBC Four\u2019s The Sky at Night<\/em>.<\/p>\n \u201cNamed NGC 5953 and 5954, these two spiral galaxies are colliding, and you can see material from 5954 being twisted and distorted by the gravitational pull of its neighbour.\u201d<\/p>\n Read more about galaxies:<\/strong><\/p>\n However, it\u2019s unlikely to be the case that one galaxy is stronger than the other.<\/p>\n \u201cThey\u2019re about the same size, so my guess is that it\u2019s a sort of mutual attraction,\u201d says Lintott. \u201cTheir gravity will be pulling on each other.\u201d<\/p>\n When they do finally collide, their stars will actually remain separate.<\/p>\n \u201cWhile you won\u2019t get a stellar collision, the gas in the galaxy is being distorted and energised so you\u2019ll get a spectacular burst of star formation. These galaxies are about to light up like fireworks.\u201d<\/p>\n Once the initial collision has happened, Lintott explains that the galaxy will begin to settle down. But the form which this new galaxy will take is still unknown.<\/p>\n \u201cSometimes when you collide two spiral galaxies<\/a> like these, you get a nice big elliptical galaxy \u2013 basically the big ball of stars.\u00a0But sometimes we think that a new spiral galaxy will form. And we don\u2019t know yet which of those two things will happen.\u201d<\/p>\n The final stage of the collision will be when the two galaxies\u2019 black holes merge.<\/p>\n \u201cLarger galaxies have black holes at centre, and eventually the two black holes will merge to form a bigger black hole. People are now beginning to think about how to build experiments to detect the merging of those black holes through gravitational waves.\u201d<\/p>\n These two galaxies together are called Arp 91, because they were listed in Halton Arp\u2019s 1966 Atlas of Peculiar Galaxies.<\/em> This particular photograph was taken by a group being led by Julianne Dalcanton, who are aiming to take pictures of lots of these peculiar galaxies.<\/p>\n \u201cWe\u2019re also looking for unusual things found by volunteers as part of our Galaxy Zoo Project<\/a>, including lots of these mergers,\u201d says Lintott.<\/p>\n More great space photography:<\/strong><\/p>\n![\""Prof\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/4\/2021\/11\/Andromeda_Galaxy_seen_in_visible_light-b29ae66.jpg?quality=90&resize=620%2C844"\" "\\"\"Prof\\"\/")
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